Auxiliary power unit nacelle compartments must be carefully ventilated to avoid “dead air” zones where flammable gases may undesirably collect and thus pose a potential fire threat. The compartment, however, despite the best efforts of designers does inevitably have zones where the ventilation is less than ideal, and thus fireproofing measures are not only desirable, but government regulations also require certain levels of fireproofing be present. Thus, for example, when a fire is detected in the compartment, typically a fire-suppressing liquid (such as halene) is dispensed into the compartment to control the flames. Fire resistant materials are also used in construction. For example, oil coolers in such systems are often constructed of stainless steel or the like, to provide fire protection should a fire occur in the compartment while the auxiliary power unit is in operation. The stainless steel provides better heat resistance (relative to generally preferred lighter-weight materials like aluminium, etc.) to the oil in the cooler in the presence of the high temperatures of a nearby fire. Such measures add weight to the overall design, however, and thus it would be desirable to provide improved, lighter weight measures for providing fire protection.